LUXEMBOURG (AFP) - US software giant Microsoft appealed a stinging EU anti-trust ruling that saw it fined half a billion euros (dollars) for abusing its market dominance.
Bill Gates's software titan initially is pressing the European Union's top court to suspend measures ordered against it by the European Commission in March, although the case itself is expected to last years.
After a marathon competition inquiry, the commission decided that the company had to offer a version of its operating system Windows without its Media Player software, which offers access to audio and video content.
The commission, the EU's executive arm, also required Microsoft to provide competitors with the information they needed to enable their products to communicate with Windows.
The money from the fine has been paid into an escrow account, meaning it is held in trust and neither Microsoft nor the commission has access while the appeal is pending.
Microsoft has filed two suits: one seeking to overturn the March ruling, the other to suspend the "remedies" imposed by Brussels. The latter was the case due to be heard in Luxembourg on Thursday, Friday, and possibly into Saturday.
About 10 other firms are presenting their case in Luxembourg, including companies like RealNetworks and Novell, while groups such as the Association for Competitive Technology (ACT) and the Computer and Communications Industry Association (CCIA) will also take the stand.
Microsoft lawyers insisted that the company should not have to give technology secrets to its rivals because these are protected by patents.
Speaking before the hearing began, Microsoft chief lawyer Brad Smith said that unbundling Windows Media Player would prove disastrous. "That is a precedent that is going to undermine European consumers and European competitiveness."
But the commission said Microsoft was wrong to say it would suffer irreparable harm from disclosing the information and that any possible infringement of intellectual property rights would only have a temporary effect.
"Any interference will be temporary in nature and therefore not irreversible," said Walter Moells, a lawyer for the Commission.
Supporters of the Brussels ruling stressed the need to implement the judgment. Jeremy Allison of software developer Samba said Microsoft's rivals had lots of new ideas for products that they want to put on the market.
"The remedies in my opinion are extremely necessary in order to restore competition," he said.
Microsoft's rivals are fiercely opposed to any suspension of the measures ordered against it. They argue that such a ruling would open the way for Microsoft to extend its dominance further.
"You've already seen them eliminate competition on the browser market," said CCIA lawyer Thomas Vinje, arguing that the bundling of software like Media Player is "the most anti-competitive weapon Microsoft has employed."
He notably voiced concern that, after audio and video software, Microsoft could use its dominance to similar effect for example in the mobile telephony software market.
Microsoft, while hoping for a positive ruling, says it is also prepared for the worst, its chief lawyer said.
"We obviously think that having to comply really would cause great harm not only to us as a company but to great many others in our industry... But nonetheless if we're ordered to comply we'll be in the position to to do so."